It is known that it is difficult to achieve watertightness in the casing of instruments, especially watches, that have to be able to work in a fluid environment of which the penetration into the casing would damage the mechanisms contained therein.
Various solutions are also known which aim to provide sealed closure of the casing and which involve a seal acting on the shaft of the winding button which has to be rendered watertight or acting on a part which is rigid with or in one piece with the shaft or which in any case constitutes a part thereof functionally.
In some types of watch, for example, watches for underwater immersion or watches having a double time zone and the like, it is also known that there is a problem involved in locking the rotatable bezel carrying particular operational information, for example, the decompression times for underwater watches. This locking prevents a situation where, after the setting of the bezel in accordance with requirements, the bezel may change its position accidentally, thus rendering its setting void and creating a potentially dangerous situation for the diver who no longer has the required information and, what may be worse, is unaware of the unreliability and incorrectness of the information with which the bezel nevertheless provides him.
In the majority of commercial watches, this positive locking does not exist and the resistance which the bezel has to rotation owing to the friction of the resilient members which maintain the bezel in position is normally relied upon to prevent undesired rotation of the bezel.
Only in some watches, which are of particularly high quality and which are therefore expensive, is the locking in question obtained by means of a special structure of the bezel, which has to be pushed downwards to disengage it from its support and to permit rotation thereof.
CH 673 197 A discloses a device for application to watched having various features disclosed in this specification.
FR 1 166 504 A discloses a device for ensuring water-tightness of underwater watches though the action of pressure means capable of maintaining a button pressed on a seal.
GB 364 878 A discloses a watch with a button connected integrally to a sleeve element forming an annular groove wherein a seal is carried.